1. Field of the Invention
This invention relates generally to devices used to clear obstructions in body passageways, more particularly, this invention relates to apparatuses and methods of treating such obstructions by the infusion of chemical thrombolytic agents. Yet more particularly, this invention relates to catheters and to catheter systems for exposing vascular obstructions to therapeutic agents, generally to effectuate their removal.
2. Description of the Prior Art
The use of catheter systems to treat various medical conditions has been known for some time. In treating a particular area within a body passageway, it is often desirable to isolate the area to be treated from the rest of the body. One approach to isolating a treatment area is the placement of one or more inflatable balloons proximal or distal (or both) to the treatment area. Inflating the balloon or balloons serves to isolate the vascular structure to be treated and permits control of the length of time of exposure. U.S. Pat. No. 2,936,760 issued to Gants, U.S. Pat. No. 4,022,216 issued to Stevens, and U.S. Pat. No. 4,705,502 issued to Patel describe catheters designed for use in the urinary tract.
Catheter systems are also used in other applications. U.S. Pat. No. 4,696,668 issued to Wilcox, for example, describes a catheter system for treatment of nasobiliary occlusions. Similarly, U.S. Pat. No. 4,198,981 issued to Sinnreich is used in intrauterine applications. U.S. Pat. No. 4,453,545 issued to Inoue discloses an endotracheal tube.
One of the most common applications for catheter systems is the treatment of occlusions within the cardiovascular system. A catheter system for venous applications is seen in U.S. Pat. No. 4,795,427 issued to Helzel. U.S. Pat. No. 4,636,195 issued to Wollinsky, U.S. Pat. No. 4,705,507 issued to Boyles, and U.S. Pat. No. 4,573,966 issued to Welkl et al., all describe catheter systems designed to infuse a liquid for the treatment of an arterial occlusion. Each of these devices has one or more balloons which can be inflated to occlude the artery during the treatment process.
U.S. Pat. No. 4,655,746 issued to Daniels et al. discloses the use of two concentric catheters defining an interlumenal space therebetween. Each of the catheters has its own balloon to isolate (adjustably) a portion of the body passageway. The Daniels et al. design, however, requires the use of the interlumenal space as a fluid passageway, thereby complicating the construction and operation of the device.
U.S. Pat. No. 4,927,418 to Dake et al. discloses a catheter for uniform distribution of therapeutic fluids. The Dake et al. catheter utilizes a relatively thick-walled tubular body having a plurality of smaller lumens therein in conjunction with a larger central lumen discharging fluid from the catheter.
U.S. Pat. No. 5,059,178 to Ya uses balloons to subtend a blood vessel upstream and downstream of a thrombus. Thrombus dissolving agent is supplied to the zone between the balloons. An expansion catheter having a third balloon is used to expand a location of structure remaining after removal of the dissolved thrombus.